Terminal clip and distributing block



Feb. 23, 1937. J B TERRlLL' JR 2,071,713

TERMINAL CLIP AND DISTRIBUTING BLOCK Filed May 25, 1932 2 Sheets-Sheet lI%Z WWWM FIG. 3

INVENTOR- J. B. TERRILL JR.

si ma r30 TORNEY- FIG. 7

Feb. 23, 1937. J, B TERRILL, JR 2,071,713

TERMINAL CLIP AND DISTRIBUTING BLOCK Filed May 25, 1932 2 Sheets-Sheet 2FIG. IO

FIG. II

[N V [:N TOR Jv B- TERRILL JR.

Patented Feb. 23, 1937 UNITED STATES PATENT OFFICE TERMINAL CLIP ANDDISTRIBUTING BLOC Application May 25, 1932, Serial No. 613,535

8 Claims.

This invention relates to a terminal clip and a distributing blockemploying such clip. More particularly it relates to such apparatus foruse in terminating cable conductors and making cross-connections ondistributing frames and similar terminals.

In a copending application of L. H. Rovere et al., Serial No. 438,481filed March 24, 1930 and entitled Switchboard terminal block, for which,Letters Patent No. 1,961,111 were granted May 29, 1934, there is shown aterminal block for use on the distributing frame of a telegraphswitchboard, the elements of the block being so arranged as to permit ofa multitude of connections being made between the switchboard and thedistributing frame and also, by the use of a separate block, permittingconnections to be made between the distributing frame and the incomingand outgoing conductors. The terminal block of the aforesaid applicationincludes a plurality of rows of terminal strips, the rows extendinglongitudinally of the block and being superimposed one above the otherin tiers. The terminal strips extend transversely of the block and eachstrip is provided with a soldering lug at each end thereof. thecorresponding strips of each row being in alignment, one over the other,and each pair of rows being shorter than the preceding pair to produce apyramided construction, thus separating the terminal lugs in such manneras to permit separate fanning openings to be provided for each lug. Theterminal blocks may be arranged on the horizontal and vertical sides ofthe distributing frame in such manner that the switchboard and incomingline connections are made. to the lugs on one side of their respectiveblocks and the cross-connections between horizonal and vertical sides ofthe frame, by which changes are ordinarily made in the permanentassignments of the lines, are secured to the lugs on the opposite sideof the terminal blocks.

All conductors are soldered to their respective lugs and changes inassignment can only be. made by removing the soldered connections and-resoldering the conductors in a new location. While this block isexceptionally well suited for use where the wire assignments arerelatively permanent, it is desirable in certain instances to providequick detachable connections for the conductors terminating in suchblocks. However the usual form of detachable clips are not suited forthis purpose, since they do not permit of the necessary concentration ofa large number of such clips in a restricted space and do not providesufficient grip to insure a safe connection and to give the requiredelectrical contact with the conductor necessary in telegraph circuits,where the signal currents are low and the receiving apparatus sensitive.

It is one of the objects of the present invention therefore to provide aquick detachable clip which is extremely strong, producing a firm gripon the conductor, and which is of small size whereby a large number ofsuch clips may be confined in a restricted space and so arranged as toenable a multitude of connections to be made thereto.

Another object is to provide a detachable clip for current conductorswhich, while of small size permits a relatively large movement of thejaws so as to accommodate conductors of varying sizes.

Another object is to produce such a clip which is well adapted forswitchboard terminal blocks and which requires substantially no morespace than that occupied by the usual type of soldering lugs.

A further object is to provide a terminal block containing a multitudeof terminal strips having spring jaws for detachably engaging theassociated conductors, which may be quickly assembled and in which theterminal clips are firmly held in the insulating portions of a block.

Other objects and advantages of the invention will appear as thedescription proceeds.

In accordance with my invention I preferably construct the clip of twospring arms terminating in cooperating jaws, the spring arms beingfulcrumed on each other with a relatively short leverage whereby alarge. gripping force may be obtained at the jaws with a safe bendingmoment at the point of fulcrum and in order to obtain the requisitemovement of the jaws to accommodate conductors of various sizes andpermit of their ready insertion into the jaws I so shaped the arms ofthe clip as to produce a constantly shifting fulcrum as the jaws aremoved to a wire receiving position. The short leverage enables a stronggrip to be produced with a given bending moment and the progressivelyshifting fulcrum enables a large jaw opening to be obtained withoutunduly straining the arms of the clip at any point, the strain beingdistributed over a substantial length of the resilient arms of the clip.

I prefer to construct one of the arms of a metal having a good contactconductivity with the conductor, such as phosphor-bronze and the otherarm of a stiff resilient metal such as springsteel although it is to beunderstood that both arms may be composed of the same material and onemay be rigid if desired whereby the entire strain is taken by the otherarm. The clip inay take different forms as will appear hereinafter andis appliable to a variety of uses, some of which are included herein.

One preferred use of the clip is the construction of a switchboardterminal block in which a large number of terminal strips must beconfined in a restricted space. In accordance with one modification ofthe invention, the terminal strips of the blocks may terminate in aclip, the spring arms of which are so shaped as to hold the strips inplace in their respective slots in the insulating portions of the block,due to their resiliency. The confining walls of the slot, at the sametime, serve to hold the arms of the clip under an initial strain therebyassisting in the gradual accumulation of the gripping force thereof.

The invention will be more fully understood by reference to theaccompanying drawings in which:

Figure l is a plain view'of a distributing block embodying terminalstrips constructed in accordance with the present invention;

Figure 2 is a vertical sectional view on the line 2-2 of Figure 1;

Figure 3 is an end elevation of a block similar to that shown in Figure1 but employing terminal strips having both ends terminating indetachable clip members;

Figure 4 is an end elevation of a terminal block having four tiers ofterminal strips;

Figure 5 is a side view of a terminal strip embodying the presentinvention;

Figure 6 is a similar view of the terminal strip in position in a slotof a distributing block;

Figure 7 is a further view of the terminal strip in position to engage aconductor;

Figure 8 is a front view of the terminal strip;

Figure 9 is a fragmentary side view partly in section substantially onthe line 99 of Figure 4 showing the manner of connecting conductors tothe terminal strips;

Figure 10 is an elevation of a modified form of terminal block;

Figure 11 is an end view of the block shown in Figure 10; t

Figure 12 is a fragmentary perspective view of a further form ofterminal block;

Figure 13 illustrates the form of the strip used in the block of Figure12; and 7 Figures 14 and 15 are side and front views respectively of a.different form of terminal clip Referring first to Figures 5 to 8, aterminal strip suitable for a terminal block is shown, comprising a mainbody portion 16 composed preferably of phosphor-bronze and terminatingat one end in a soldering lug I1 and having at the other end a curvedresilient arm. i8 terminating in a jaw member l9, forming one element ofa clip embodying my invention. The other element of the clip is composedof a strip 20 of stiff resilient metal such as spring-steel welded orotherwise suitably secured to the body portion E6. The strip 20 has acurved spring arm 2i and terminates in jaw portion 22. The jaw 22 isslotted at 23 to receive the narrowed end of the jaw iii in the usualmanner, as is clearly shown in Figure 8.

The arms l8 and 2| of the clip, at the point (a) of divergence arecurved outwardly in a slow arc whereby, as the jaws are pressed toaovrmsgether, for instance from the position shown in Figure 5 to that shownin Figure 6, the arms fulcrum about the point (a) in an engagement whichgradually shifts the fulcrum point outwardly towards the jaws to a point(1)) (Figure 6) and as the jaws are further compressed as shown inFigure 7, the fulcrum is shifted to a point (0). This shifting of thefulcrum permits the stress to be gradually absorbed by the spring armsover the distance a-c, thereby permitting a relatively wide movement ofthe jaws which makes possible the easy insertion and secure gripping ofconductors of various sizes without material distortion of the arms atany point. The jaws therefore may be made of an extremely stiff materialwithout danger of distorting them beyond their elastic limit at anypoint. Due to the gradual shifting of the fulcrum point and consequentshortening of the leverage, the force applied at the jaws for a safebending moment at the fulcrum point increases as the jaws are pressedtogether and due to the relatively short leverage this force assumesconsiderable magnitude enabling a strong gripping action of the jaws onthe conductor 24 to be obtained.

The radius of curvature of the diverging portions of the strip may be sochosen, for each member, that the surfaces when brought together, bycompression of the ends, will remain in continuous contact throughoutthe area over which the fulcrum has moved. This curvature varies withthe nature and dimensions of the members and can be readily determined,with sufficient accuracy, by trial and error.

When the clip is employed in a terminal block of the type shown in theaforesaid application of L. H. Rovere, I prefer to mount the strip in aslot 25 (Figure 6), one end I! of the terminal strip being offset to theside of the slot, as 26, and the two resilient arms [8 and 2| beingcompressed together in the opposite end of the slot whereby the strip isfirmly retained in place. The compression of the arms I8 and 2| betweenthe confining walls of the slot also applies an initial tension to thejaw members assisting in the gradual building up of a gripping forcetherein. Referring now to Figures 1 and 2, I have shown a distributingblock of the general form disclosed in the aforesaid application of L.H. Rovere and utilizing the terminal strip just described. This blockcomprises two rows of terminal strips 28 and 29, the strips extendingthrough transverse slots 25 in the various insulating members and havingone end 3| offset to the side of the slot and terminating in thesoldering lug H. The opposite end of the terminal strips terminate inthe jaw members l9 and 22. The terminal block assembly comprises a wideinsulating terminal strip retaining member 33 and a narrow insulatingterminal strip retaining member 34, separated by an insulating spacer35. The assembly is mounted upon an insulating base 36 by means ofclamping bolts 3'! and the base 36 is provided with individual fanningopenings 38 for each end of each of the terminal strips.

When a terminal block of this type is employed on a distributing frame,the connections from the switchboard are made permanently to thesoldering lugs I! of the blocks on the horizontal side of the frame andthe incoming lines are connected permanently to the soldering lugs ofcorresponding blocks on the vertical side of the frame.Cross-connections between the horizontal and vertical side of the framecan then be made between the clips, thus permitting thesecross-connections to be changed readily so as to associate eachswitchboard section with any desired ones of the incoming and outgoinglines.

Figure 3 shows a block differing from that shown in Figures 1 and 2 onlyin the use of clips on each end of the terminal strip. This block is ofuse where all of the connections to the block are of a temporary orsemi-permanent nature.

The block shown in Figure 4 is for use where a greater number ofconductors must be terminated in a restricted space, substantially twicethe same terminal facilities being provided in the same space with thisform as with the previous forms.

The manner of attaching the cabled conductors to the clips is shown inFigure 9. The end of each conductor 24 is bored and bent in the form ofa hook as shown at 39. The hook end is then inserted through the fanningopenings 3|! and while the jaws are pressed together, as with a pair ofpliers. The hooked end is pulled downwardly between the jaw members andthe jaws released. When so connected the conductors are firmly held intheir associated clips and it is practically impossible to remove themby a pull exerted thereon from the exterior of the block. As is evidentin Figure 9 a large number of such conductors may be terminated in arestricted space without danger of accidentally contacting between theindividual conductors or between a conductor and unassociated terminalclip.

In Figure 10 I have shown a form of distributing block which providesthe facilities of both the horizontal and vertical sides of thedistributing frame. This block is particularly adaptable for citydistribution service, as for instance, in the case of cable conductorsentering an ofiice building for distribution to a plurality of officesthroughout the building. The lower half of the block may be consideredas equivalent to the incoming or vertical side of the distributing frameand the upper half thereof as the equivalent of the horizontal side. Asshown each half of the block comprises two insulating terminal carryingstrips 40 and 4! stepped at their left sides, as shown in Figure 11, andhaving slots for the reception of a number of L shaped terminal strips,the vertical arms of which terminate in soldering lugs and thehorizontal arms in detachable clips. The two rows 42 and 43 of terminalstrips are staggered longitudinally of the block and provided withindividual fanning openings 63. The upper and lower halves of the blockare spaced by an insulating section 44 and are secured together byclamping bolts 45.

In the use of this block the cable 46, entering the building, may befanned to the lower row of soldering lugs and the cable 41, composed ofconductors extending to various oflices throughout the building, may befanned to the upper set of soldering lugs. These connections arepermanent. Cross connections between the incoming conductors 46 and theconductors 41, are made by patching loops 48 extending from the lowerclips 42, 43 to the upper clips, preferably around the end of the block,as shown in Figure 10. By means of these patching loops any incomingconductor may be connected to any of the oflice conductors 41 and theassignments changed quickly when required. Due to the fact that thepatching loops extend around the sides of the block, the face thereof isleft unobstructed,

thereby rendering all of the clips available for changing assignmentsand for inspection. The clips are all contained within the recessedportion formed by the stepped sections of insulation and, therefore,they are protected from accidental contact and, if desired, a cover maybe provided for the open end of the block. It is to be understood,however, that the block as normally used is enclosed in a metalliccasing in the usual manner.

In Figure 12 a still further form of distributing block is shown whichprovides facilities for both permanent and detachable connections. Inthis form the terminal strips are shaped as shown in Figure 13, thehorizontal arms terminating in soldering lugs and the upper vertical armin a detachable clip. The lower vertical arm is received in a slot inthe insulating body 53 and the tabs 54 formed on the lower end thereofare bent in opposite directions to lock the strip securely in theinsulating body. The insulating body is provided with outwardlyextending flanges 55, having fanning openings through which theconductors may pass to adjacent the soldering lugs.

In normal use one set of conductors may be permanently attached to thesoldering lugs 49 and the other ones extended to the detachable clips.After the circuits have been completely tested and the assignmentsdetermined to be permanent, the second set of conductors may be removedfrom the clips and permanently soldered to the lugs 50. This provides anextremely handy arrangement for making the initial assignment andpermitting them to be shifted until their permanent location has beenestablished.

It will be appreciated that in all the terminal blocks described the useof the detachable clips is possible only because of the specificconstruction thereof, whereby a strong gripping action is obtained witha clip of small dimension.

In Figures 14 and 15 a somewhat slightly different clip is shown, inwhich the jaw members 60 and GI have a biting engagement with theconductor, the two arms being cut away and crossing over each other at62 in the manner of a pair of tongs. The arms are curved outwardly,however, adjacent their point of divergence so as to provide a shiftingfulcrum, thereby permitting a relatively large opening to be obtainedwith short lever arms composed of relatively stiff material.

It is obvious that the clip may take a-variety of other shapes withoutdeparting from the essential features thereof and may be applied to alarge variety of uses. Therefore, I do not desire to be limited to theparticular form of clip or to the distributing block employing the same,shown herein, but contemplate all modifications and changes thereinwithin the terms of the appended claims.

What I claim is:

1. A terminal clip for an electric conductor comprising a pair ofcooperating conductor gripping jaw supporting members, one of which iscomposed of a metal of good contact conductivity and the other of whichis composed of a stiff resilient material of a different nature, saidjaw supporting members} being fulcrumed on each other and curvedoutwardly relative to each other over a substantial portion of theirlength so as to produce a shifting fulcrum as the members are pressedtogether to open said jaws.

2. A terminal clip for an electric conductor crumed on each other,cooperating conductor gripping jaws carried by said members, at leastone of said members being convexed with relation to the other over asubstantial portion of their length so as to produce a shifting fulcrumas the members are pressed to conductor receiving position and means forapplying a constant compressive force to said members along a convexportion thereof to produce an initial tension in the jaws.

3. A terminal clipfor an electric conductor comprising a pair ofsupporting members, fulcrumed on each other, cooperating conductorgripping jaws carried by said members, at least one of said membersbeing convexed with relation to the other over a substantial portion oftheir length so as to produce a shifting fulcrum as the members arepressed to conductor receiving position, a support for said memberscomprising confining wall portions engaging a convex portion of saidmembers to hold them under an initial compression.

4. A terminal clip for an electric conductor comprising a pair ofoppositely disposed jaw carrying strips, a support for said stripscomprising an insulating body having an elongated slot therein, saidstrips having flexible diverging portions, said diverging portions beingpartially compressed together and a substantial part of said divergingportions being contained within said slot, whereby the strips are heldin an initial compression by the walls of said slot and exert an outwardforce thereagainst.

5. A terminal block comprising an insulating support having a pluralityof parallel transverse slots therein, a terminal strip contained in eachof said slots, said strips comprising a central body portion withoutwardly projecting terminals, at least one of said terminalscomprising a pair of diverging resilient members partly compressedwithin the slot, whereby the strips are held under an initialcompression by the walls of said slot and exert an outward forcethereagainst, said resilient member having cooperating wire grippingportions externally of the slot.

6. A terminal block comprising an insulating support, a group ofL-shaped terminal strips extending therethrough, said strips havingconductor engaging terminals projecting outwardly through two adjacentsides of the support and a second group of L-shaped terminal strips alsoextending through said support and having conductor engaging terminalsprojecting outwardly through adjacent sides of the support, at least oneof said latter sides being a different side from either of said firstmentioned sides.

'7. A terminal block comprising a support having a group of terminalstrips extending therethrough and terminating at one end in solder inglugs and in the opposite ends in wire gripping jaws, and a second groupof corresponding terminal strips extending through said support andbeing spaced from the first set, individual cabled conductors extendingto the soldering lugs of each group of terminal strips and loopedconductors extending between the wire gripping jaws of one group andthose of the other group said looped conductors being disposed to a sideof the block different from that adjacent whichthegripping jaws arearranged whereby said looped conductors do not interfere with freeaccess to said gripping jaws.

8. A terminal block comprising an insulating support having a recessedside, a group of terminal strips extending through said support, havingone end terminating in wire engaging clips contained within said recessand the other ends extending outwardly from an adjacent side of thesupport, a second group of terminal strips extending through saidsupport and also having one end terminating in wire engaging clipscontained within said recess and the opposite ends projecting outwardlyfrom the opposite adjacent side.

JOHN B. TERRILL, JR.

